摘要
基于粒子群优化算法的CALYPSO晶体结构预测结合第一性原理计算,研究了块体SnS、纳米单层、双层及三层SnS的晶体结构和电子结构.研究发现,受层间分子间力的影响,单层、双层和三层SnS在常压下最稳定的结构虽然都为正交结构,但不同于块体的Pnma空间群,单层SnS的空间群为C2/m,双层和三层SnS的空间群为P4mm.进一步的电子性质研究发现,层数对二维SnS带隙具有调控作用,带隙随着层数的减少而增加,纳米单层、双层及三层SnS的带隙分别为1.35 eV、0.24 eV、0.17 eV;所有结构中的Sn原子和S原子之间为极性共价键,而且随着层数的增加,Sn原子向S原子转移的电荷量减小,电荷局域程度减小,成键性加强.本研究将对少层SnS的合成,以及其在太阳能电池和热电领域的应用等方面提供理论指导.
By combine the crystal structure prediction methods based on particle swarm optimization algorithm with the first-principles calculations,we have systematically studied the crystal structures and the electronic properties of bulk SnS,monolayer SnS,bilayer SnS and trilayer SnS.The results show that due to the influence of the intermolecular forces between the layers,the most stable structures of monolayer,bilayer and trilayer SnS at ambient pressure are all orthogonal structures,but they are different from the bulk SnS(Pnma).The space group of monolayer SnS is C2/m,both bilayer SnS and trilayer SnS are P4mm.The calculation results of electronic properties show that the number of layers will effectively modify the electronic structures.For example,the band gaps of monolayer,bilayer and trilayer SnS are 1.35 eV,0.24 eV,and 0.17 eV respectively;There are polar covalent bonds between Sn and S atoms in all structures.The electrons are mainly localized around S atoms.With the number of layers increasing,the amount of charge transferred from Sn to S atoms decreases and the degree of charge localization decreases,and the bonding is strengthened.The research will provide theoretical guidance for the synthesis of few-layer SnS and its application in the field of solar cells and thermoelectrics.
作者
孙梦
武晓倩
刘亭亭
苏宁宁
SUN Meng;WU Xiao-qian;LIU Ting-ting;SU Ning-ning(School of Science, North University of China, Taiyuan 030051, China)
出处
《陕西科技大学学报》
北大核心
2021年第2期176-182,共7页
Journal of Shaanxi University of Science & Technology
基金
山西省自然科学基金项目(201801D221035)
山西省高等学校科技创新项目(2019L0551)
中北大学科研基金项目(XJJ201827,XJJ201820)。
关键词
晶体结构
层状SnS
电子结构
crystal structure
layered SnS
electronic structure
